JP2007232774A - Developing roll and magnet roll used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roll having magnet blocks decreased in number without changing the number of poles of a magnetic force pattern, and a magnet roll used therefor. <P>SOLUTION: In the developing roll 10 and magnet roll 14, two magnet blocks 20A and 20C each have two magnetic pole peaks corresponding to respective magnetic poles of flanks 20c and 20d and an outer peripheral curved surface 20b. Namely, the one magnet block 20 forms two magnetic pole peaks. Consequently, the number of magnet blocks is decreased to three while five poles of a magnetic force pattern M1 are maintained (i.e. without changing the number of poles), and the number of the magnet blocks 20 of the magnet roll 14 is less than that of conventional techniques requiring magnet blocks as many as or more than the poles of the magnetic force pattern. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing roll used in an electrophotographic developing device such as a copying machine, a facsimile machine, and a printer, and a magnet roll used therefor.

  Conventionally, as a developing roll used for an electrophotographic developing device or the like, a developing roll including a magnet roll having a plurality of magnetic poles formed on its surface and a cylindrical sleeve enclosing the magnet roll is as follows. It is disclosed in Patent Document 1 and the like. In such a developing roll, only the outer sleeve is rotated with the shaft of the magnet roll fixed, so that the developer stored in a predetermined developer container is pumped up and adsorbed on the surface of the sleeve. Then, the developer is conveyed to the development area. The developer conveyed to the development area is supplied to the photosensitive drum, and the electrostatic latent image formed on the surface of the photosensitive drum is visualized. The developer remaining on the sleeve side without being supplied to the photosensitive drum is peeled off from the sleeve when it reaches the developer peeling region by the rotation of the sleeve.

That is, since the developing roll repeats the process of pumping up the developer, layer regulation, conveyance, development, and peeling as described above, it is necessary to form a plurality of magnetic poles on the surface of the developing roll. However, when such a plurality of magnetic poles are formed on the surface of the cylindrical magnet, the magnetic pattern that can be designed is limited, and in order to satisfy the magnetic pole that generates the highest magnetic force among the plurality of magnetic poles. Must be made of a more expensive magnet material, and the degree of freedom in cost is also limited. Thus, a developing roll in which a plurality of magnet blocks magnetized to magnetic poles corresponding to a target magnetic pattern are attached around the shaft to increase the degree of freedom of the magnetic pattern of the developing roll is disclosed in, for example, Patent Document 2 below. And Patent Document 3 and the like. In these documents, in order to realize a complicated magnetic force pattern, a magnet block magnetized from the inner peripheral surface and both side surfaces toward the outer peripheral surface is disclosed.
Japanese Patent Laid-Open No. 11-84879 JP-A-62-282423 Japanese Patent Laid-Open No. 10-308307

  However, the conventional developing roll described above has the following problems. That is, when the number of poles (ie, magnetic pole peaks) of the magnetic pattern is large (for example, in the case of five poles), the number of magnet blocks is increased to be larger than the number of poles (that is, five or more). It was necessary to use a magnet block. When the number of magnet blocks is increased in this way, the manufacturing process is increased and the manufacturing time is extended.

  Accordingly, the present invention has been made to solve the above-described problems, and provides a developing roll that can reduce the number of magnet blocks without changing the number of poles of a magnetic pattern, and a magnet roll used therefor. Objective.

  The magnet roll according to the present invention has a shaft and a long magnet block attached along the shaft, and the magnet block includes a first imaginary line extending along the circumferential direction of the shaft axis. The magnet block is magnetized between the first surface and the second surface, the first surface intersecting with the second surface intersecting with the second imaginary line orthogonal to the axis of the shaft. In addition, a gap is formed on the first surface side of the magnet block.

  In this magnet roll, since the magnet block is magnetized between the first surface and the second surface, magnetic poles are formed on the first surface and the second surface of the magnet block. And this magnet roll has the magnetic pole peak corresponding to the magnetic pole of a 2nd surface as the magnetic force pattern. Moreover, since the air gap is formed on the first surface side of the magnet block, the magnet roll further has a magnetic pole peak corresponding to the magnetic pole of the first surface as the magnetic force pattern. That is, the magnet block of the magnet roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the first surface and the second surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  The magnet block further includes a third surface that intersects the first imaginary line and is different from the first surface, and the magnet block is attached between the third surface and the second surface. It may be magnetized and a gap may be formed on the third surface side of the magnet block. In this case, the number of magnetic pole peaks formed by one magnet block can be further increased.

  The magnet roll according to the present invention has a shaft and a plurality of elongated magnet blocks attached along the shaft, and the plurality of magnet blocks have a gap formed around the shaft. The end-side magnet block adjacent to the air gap among the plurality of magnet blocks is arranged adjacently along the circumferential direction of the shaft axis, and extends along the circumferential direction of the shaft axis. A first surface that intersects the imaginary line and faces the air gap, and a second surface that intersects the second imaginary line orthogonal to the axis of the shaft, and the first surface and the second surface Magnetized between the surfaces.

  In this magnet roll, since the end side magnet block is magnetized between the first surface and the second surface, magnetic poles are formed on the first surface and the second surface of the end side magnet block. Has been. And this end side magnet roll has the magnetic pole peak corresponding to the magnetic pole of a 2nd surface as the magnetic force pattern. Further, since the first surface of the end-side magnet block faces the air gap, the end-side magnet roll further has a magnetic pole peak corresponding to the magnetic pole of the first surface as the magnetic force pattern. Yes. That is, the end-side magnet block of the magnet roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the first surface and the second surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  Further, among the plurality of magnet blocks, the middle magnet block having magnet blocks on both sides includes a fourth surface intersecting with the first imaginary line, and a fifth surface intersecting with the second imaginary line. , Having a sixth surface that intersects the first imaginary line and is different from the fourth surface, and between the fourth surface and the fifth surface, and between the sixth surface and the second surface. It may be magnetized between the five surfaces. In this case, the magnetic pole peak corresponding to the magnetic pole of the fifth surface in the middle magnet block is increased.

  The magnet roll according to the present invention has a shaft and a long magnet block attached along the shaft, and the magnet block includes a first imaginary line extending along the circumferential direction of the shaft axis. The seventh surface intersects with the first virtual line and has an eighth surface different from the seventh surface, and the magnet block is between the seventh surface and the eighth surface. And a gap is formed on the seventh surface side and the eighth surface side of the magnet block.

  In this magnet roll, since the magnet block is magnetized between the seventh surface and the eighth surface, magnetic poles are formed on the seventh surface and the eighth surface of the magnet block. And since the space | gap is formed in the 7th surface side and 8th surface side of a magnet block, this magnet roll respond | corresponds to each of the magnetic pole of the 7th surface and the 8th surface as the magnetic force pattern. It has a magnetic pole peak. That is, the magnet block of the magnet roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the seventh surface and the eighth surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  A developing roll according to the present invention includes a pair of a magnet roll having a shaft and a long magnet block attached along the shaft, a cylindrical sleeve for housing the magnet roll, and a pair of openings attached to the end openings of the sleeve. The magnet block includes a first surface that intersects with a first imaginary line orthogonal to the axis of the shaft, and a second surface that intersects with a second imaginary line extending in the circumferential direction of the shaft axis. The magnet block is magnetized between the first surface and the second surface, and a gap is formed on the second surface side of the magnet block.

  In this developing roll, since the magnet block is magnetized between the first surface and the second surface, magnetic poles are formed on the first surface and the second surface of the magnet block. And this magnet roll has the magnetic pole peak corresponding to the magnetic pole of a 2nd surface as the magnetic force pattern. Moreover, since the air gap is formed on the first surface side of the magnet block, the magnet roll further has a magnetic pole peak corresponding to the magnetic pole of the first surface as the magnetic force pattern. That is, the magnet block of the developing roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the first surface and the second surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  The developing roll according to the present invention is attached to a magnet roll having a shaft and a plurality of elongated magnet blocks attached along the shaft, a cylindrical sleeve for accommodating the magnet roll, and an end opening of the sleeve. The plurality of magnet blocks are arranged adjacent to each other along the circumferential direction of the shaft axis so that a gap is formed around the shaft. Of these, the end side magnet block adjacent to the air gap intersects the first imaginary line extending along the circumferential direction of the shaft axis and is orthogonal to the shaft axis and the first surface facing the air gap. The second surface intersects the second imaginary line, and is magnetized between the first surface and the second surface.

  In this developing roll, since the end magnet block is magnetized between the first surface and the second surface, magnetic poles are formed on the first surface and the second surface of the end magnet block. Has been. And this end side magnet roll has the magnetic pole peak corresponding to the magnetic pole of a 2nd surface as the magnetic force pattern. Further, since the first surface of the end-side magnet block faces the air gap, the end-side magnet roll further has a magnetic pole peak corresponding to the magnetic pole of the first surface as the magnetic force pattern. Yes. That is, the end side magnet block of the developing roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the first surface and the second surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  Further, among the plurality of magnet blocks, the middle magnet block having magnet blocks on both sides includes a fourth surface intersecting with the first imaginary line, and a fifth surface intersecting with the second imaginary line. , Having a sixth surface that intersects the first imaginary line and is different from the fourth surface, and between the fourth surface and the fifth surface, and between the sixth surface and the second surface. It may be magnetized between the five surfaces. In this case, the magnetic pole peak corresponding to the magnetic pole of the fifth surface in the middle magnet block is increased.

  A developing roll according to the present invention includes a pair of a magnet roll having a shaft and a long magnet block attached along the shaft, a cylindrical sleeve for housing the magnet roll, and a pair of openings attached to the end openings of the sleeve. The magnet block includes a seventh surface that intersects the first imaginary line extending along the circumferential direction of the axis of the shaft, a seventh surface that intersects the first imaginary line, and the seventh surface. And the magnet block is magnetized between the seventh surface and the eighth surface, and the seventh surface side and the eighth surface side of the magnet block Gaps are formed in the.

  In this developing roll, since the magnet block is magnetized between the seventh surface and the eighth surface, magnetic poles are formed on the seventh surface and the eighth surface of the magnet block. And since the space | gap is formed in the 7th surface side and 8th surface side of a magnet block, this magnet roll respond | corresponds to each of the magnetic pole of the 7th surface and the 8th surface as the magnetic force pattern. It has a magnetic pole peak. That is, the magnet block of the developing roll according to the present invention has at least two magnetic pole peaks corresponding to the magnetic poles of the seventh surface and the eighth surface. That is, the formation of a plurality of magnetic pole peaks is realized with one magnet block, thereby making it possible to reduce the number of magnet blocks without changing the number of poles of the magnetic pattern.

  ADVANTAGE OF THE INVENTION According to this invention, the developing roll which can reduce the number of magnet blocks, without changing the number of poles of a magnetic pattern, and the magnet roll used for it are provided.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a developing roll and a magnet roll used therefor according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps. In addition, the present invention is not limited to the following embodiment, and is merely an embodiment.

  FIG. 1 is a schematic perspective view of a developing roll 10 according to an embodiment of the present invention, and FIGS. 2 and 3 are a sectional view taken along line II-II and a sectional view taken along line III-III, respectively, of the developing roll 10 shown in FIG. FIG.

  As shown in FIGS. 1 to 3, the developing roll 10 includes a long cylindrical aluminum sleeve 12, a magnet roll 14 disposed inside the sleeve 12, and end openings 12 a and 12 b of the sleeve 12. It is comprised with a pair of flange 16A, 16B fixed by fitting.

  Further, the magnet roll 14 includes a round bar-shaped shaft 18 made of a high-strength material such as metal, and three long magnet blocks 20 (20A to 20C) fixed to the outer peripheral surface 18a of the shaft 18. It is constituted by.

  The three magnet blocks 20 have substantially the same fan-shaped cross-sectional shape as shown in FIG. Accordingly, the cross-sectional shape of the magnet block 20A will be described as an example.

Cross-sectional shape of the magnet block 20A has become the first and the arc _{A 1,} and the second arc _{A 2,} a shape formed by two line segments _L 1, _{L 2.} In the first arc A ₁ , the axial position I of the shaft 18 is the center of curvature, and has substantially the same curvature as the curvature of the outer peripheral surface 18 a of the shaft 18. The second arc A ₂ is also a axis position I is the center of curvature of the shaft 18, has the first arc A ₁ same opening angle and a large radius of curvature than the first arc A ₁ It has become. The two line segments L ₁ and L ₂ are lines that straightly connect corresponding end points of the first arc A ₁ and the second arc A ₂ .

Then, extending the provided first curved surface arc A ₁ is extended in the longitudinal direction of the magnet block 20 becomes the inner peripheral curved face 20a of the magnet block 20, likewise the second arc A ₂ is the longitudinal direction of the magnet block 20 The curved surface is the outer peripheral curved surface 20b of the magnet block 20, and a pair of planes in which the _two line segments L ₁ and L ₂ extend in the longitudinal direction of the magnet block 20 are the side surfaces 20c and 20d of the magnet block 20. It has become.

In the magnet block 20 shown in FIG. 3, the position of the center of curvature of the first arc A ₁ and the position of the center of curvature of the second arc A ₂ coincide with each other at the axial position I of the shaft 18. A magnet block in which the position of the center of curvature of the arc A ₁ of ₁ and the position of the center of curvature of the second arc A ₂ may be different. By adopting such a magnet block, the magnetic force pattern of the magnet roll can be matched with a desired pattern with high accuracy.

The first opening angle of the arc A ₁ of each magnet block 20 cross-section, are designed in accordance with the functions of the corresponding magnet block 20 may also be different from each magnet block 20, also matched May be. In the present embodiment, opening angle respective of the first arc _{A 1} of each magnet block 20 section, 80 ° (magnet block 20A), 50 ° (the magnet block 20B) and 90 ° (magnet block 20C) It has become. For example, the opening angle respective of the first arc _{A 1} of each magnet block 20 cross, 60-120 ° (magnet block 20A), from 30 to 90 ° (magnet block 20B) and 60-120 ° (magnet block 20C) Selected.

  The polarities on the outer peripheral curved surface 20b of each of the magnet blocks 20A to 20C are as indicated by reference numerals N and S in FIG. That is, the magnet blocks 20A to 20C are arranged such that the N pole, the S pole, and the N pole appear on the outer peripheral curved surface 20b, respectively. That is, the magnet blocks 20A to 20C are arranged such that the S pole and the N pole appear alternately in the forward rotation direction of the sleeve 12 (the direction of the arrow T in FIG. 3) with the magnet block 20A as the S pole.

  Each of the magnet blocks 20 is fixed to the outer peripheral surface 18a of the shaft 18 by an adhesive (not shown) at the inner peripheral curved surface 20a. The three magnet blocks 20 </ b> A to 20 </ b> C are continuously arranged adjacent to each other along the circumferential direction of the axis I of the shaft 18 in close contact with each other. That is, since each magnet block is in contact with the adjacent magnet block 20 on at least one side surface of the both side surfaces 20c and 20d, each magnet block 20 is firmly attached to the shaft 18. Further, by arranging the three magnet blocks 20 adjacent to each other, the size of the magnetic pole generated from the magnet block 20B located in the middle of the three magnet blocks 20 is increased.

  Here, the three magnet blocks 20 </ b> A to 20 </ b> C are adjacent to each other, but the shaft 18 is not completely surrounded by the magnet block 20, and the magnet block 20 is surrounded by the shaft 18. A non-existent block missing portion (void) 22 is formed. In this block missing part 22, the outer peripheral surface 18a of the shaft 18 is exposed. Such a block missing portion 22 is effective for reducing the weight and cost of the magnet roll 14.

  Each magnet block 20 is a plastic magnet or a rubber magnet composed of magnetic powder (ferrite type, Nd-Fe-B type, etc.) and resin (plastic type, rubber type, etc.). For example, as a resin used for a plastic magnet, a polyamide resin such as nylon 6 or nylon 12 can be used. Examples of rubber used in the rubber magnet include urethane rubber, acrylic rubber, isoprene rubber, and nitrile rubber. In the present embodiment, the magnet block 20B of the developing electrode that requires high magnetic properties is a plastic magnet (injected and molded by blending Sr ferrite magnet powder and polyamide resin at 90 wt% and 10 wt%, respectively). The other magnet blocks 20A and 20C are rubber magnets (Sr ferrite magnet powder and nitrile rubber blended at 90 wt% and 10 wt%, respectively, and extruded).

  Each magnet block 20 is magnetized by a known method, and the magnetization direction is as shown in FIG. That is, the magnet block 20A is concentratedly oriented and magnetized from the side surface 20c on the block missing portion 22 side toward the outer peripheral curved surface 20b, and an S pole is formed on the side surface 20c and an N pole is formed on the outer peripheral curved surface 20b. The magnet block 20B is oriented and magnetized from the outer peripheral curved surface 20b toward both side surfaces 20c and 20d, and N poles are formed on both side surfaces 20c and 20d, and S poles are formed on the outer peripheral curved surface 20b. Further, the magnet block 20C is concentratedly oriented and magnetized from the side surface 20d on the block missing portion 22 side toward the outer peripheral curved surface 20b, and an S pole is formed on the side surface 20d and an N pole is formed on the outer peripheral curved surface 20b.

  That is, the magnet block 20A and the magnet block 20C (end-side magnet block) adjacent to the block missing portion 22 are side surfaces 20c intersecting the first imaginary line K1 extending along the circumferential direction of the axis I of the shaft 18. Magnetization is performed from the side surface 20d (first surface) toward the outer peripheral curved surface 20b (second surface) intersecting the second virtual line K2 orthogonal to the axis I of the shaft 18. A block missing portion 22 is formed on the side surfaces 20c and 20d that are magnetized.

  In addition, the magnet block 20B (middle magnet block) in which the magnet blocks 20A and 20C exist on both sides, respectively, from the outer peripheral curved surface 20b (fifth surface) intersecting the second imaginary line K2, the first imaginary line K1. Is magnetized toward the side surface 20c and the side surface 20d (the fourth surface and the sixth surface) intersecting with each other.

  The magnet roll 14 described above is disposed in the sleeve 12 so as to form a gap having a predetermined interval d, and is rotatably supported by a pair of flanges 16A and 16B located at both ends of the sleeve 12. Here, the flange 16A and the flange 16B are formed with holes 24A and 24B, respectively, along the central axis thereof. Bearings 26A and 26B (rotatingly supporting the shaft 18 are provided inside the holes 24A and 24B, respectively. For example, a sintered oil-impregnated bearing is attached.

  When the developing roll 10 is installed in the developing device, the magnet roll 14 is held so as not to rotate, and only the case 28 (that is, the sleeve 12 and the pair of flanges 16A and 16B) covering the magnet roll 14 is rotatable around the shaft 18. Retained. In this state, a gear or the like is attached to the shaft portion 30 of the flange 16B, and the shaft portion 30 is rotationally driven by a motor or the like, whereby the rotation control of the case 28 of the developing roll 10 is performed.

  Next, the magnetic force pattern of the developing roll 10 described above will be described with reference to FIG.

As shown in FIG. 5, the magnetic force pattern M1 of the developing roller 10 has five magnetic poles peaks _P 1 to P _5. The five magnetic pole peaks P _{1 to} P ₅ have the polarities S, N, S, N, and S in the order of P _{1 to} P ₅ , and their functions are the pumping pole, the layer regulating pole, the developing pole, and the conveyance It is a pole and a peeling pole.

Of the _five magnetic pole peaks P _{1 to} P ₅ , the magnetic pole peaks P ₁ and P ₂ are caused by the magnet block 20A, the magnetic pole peak P ₃ is caused by the magnet block 20B, and the magnetic pole peaks P ₄ and P ₅ are magnets. This is due to the block 20C.

For each pole peak _P 1 to P _5, it will be described more specifically. Pole peak _{P 1} is due to the side surface 20c formed on the magnetic poles of the magnet block 20A (S pole). Pole peak P ₂ is due to the outer circumferential curved surface 20b formed on the magnetic poles of the magnet block 20A (N pole). Pole peak P ₃ is due to the outer circumferential curved surface 20b formed on the magnetic poles of the magnet block 20B (S pole). Pole peak P ₄ is due to the outer circumferential curved surface 20b formed on the magnetic poles of the magnet block 20C (N pole). Then, the magnetic pole peak _{P 5} is due to the magnetic poles formed on the side surface 20d of the magnet block 20C (S-pole).

That is, in the developing roll 10, the magnetic pattern M <b> ₁ having the _five magnetic pole peaks P _{1 to} P ₅ is realized using the three magnet blocks 20. This is because, in the magnet block 20A and the magnet block 20C, magnetic poles are formed on the side surfaces 20c and 20d facing the block missing portion 22, and each of these magnet blocks 20A and 20C forms two magnetic pole peaks. It is. That is, since no other magnet block 20 exists adjacent to the side surfaces 20c and 20d on which the magnetic poles are formed, the magnetic pole peaks P ₁ and P ₅ due to the magnetic poles of the side surfaces 20c and 20d are formed in the magnetic force pattern M1. Is done. In addition, in order to make the magnetic pole peak due to the magnetic poles of the side surfaces 20c and 20d appear with certainty, it is preferable that the opening angle of the block missing part 22 is a predetermined angle or more (for example, 90 ° or more). In the present embodiment, the opening angle of the block missing part 22 is 210 °.

As described in detail above, in the developing roll 10 and the magnet roll 14 described above, the magnet block 20A is magnetized from the side surface 20c toward the outer curved surface 20b, and thus the side surface 20c and outer curved surface of the magnet block 20A. A magnetic pole is formed on 20b. The magnet roll 14 as its magnetic pattern M1, and has a magnetic pole peak P ₂ corresponding to the magnetic poles of the outer peripheral curved surface 20b. Further, in order to block the missing portion 22 on the side surface 20c side of the magnet block 20A is formed in the magnet roll 14, as a magnetic pattern M1, further comprising a magnetic pole peak P ₁ corresponding to the magnetic pole sides 20c ing. Similarly, magnet block 20C also has magnetic poles formed on the side surface 20d and the outer peripheral curved surface 20b, and a magnetic pole peak P ₄ corresponding to the magnetic poles of the outer peripheral curved surface 20b. Further, in order to block the missing portion 22 is formed on the side surface 20d side of the magnet block 20C, magnet block 20C further has a magnetic pole peak P ₅ corresponding to the magnetic pole sides 20d.

  That is, in the developing roll 10 and the magnet roll 14, each of the two magnet blocks 20A and 20C has two magnetic pole peaks corresponding to the magnetic poles of the side surfaces 20c and 20d and the outer peripheral curved surface 20b. That is, two magnetic pole peaks are formed by one magnet block 20. As a result, the number of magnet blocks is reduced to 3 while keeping the number of poles of the magnetic pattern M1 at 5 (that is, without changing the number of poles), and is equal to or more than the number of poles of the magnetic pattern. The number of magnet blocks 20 of the magnet roll 14 is reduced as compared with the prior art that requires this magnet block. As a result, since the number of magnet blocks attached to the shaft 18 is reduced, the manufacturing process can be reduced and the manufacturing time can be shortened, and the yield can be improved as the magnet volume is reduced.

In addition, the magnet block 20B having the magnet blocks 20A and 20C on both sides is concentrated and magnetized from the outer peripheral curved surface 20b toward the contact surfaces 20c and 20d with the adjacent magnet blocks 20A and 20C. The magnetic pole peak corresponding to the magnetic pole of the outer peripheral curved surface 20b is increased. Further, as the magnetic pole peak increases, the magnet block 20B can be further reduced in size, thereby increasing the design freedom (size, opening angle, etc.) of the magnet blocks 20A and 20C.
(Modification 1)

Note that the above-described embodiment can be appropriately modified into a mode as shown in FIG. That is, the above-described magnet block 20B may be omitted to provide the block missing portion 22A, and a magnetic pole (S pole) corresponding to the magnetic pole of the magnet block 20B may be formed on the side surface 20c of the magnet block 20C. That is, the magnet block 20C in the magnet roll 14A shown in FIG. 6 is concentratedly oriented and magnetized from the side surface 20c (third surface) on the block missing portion 22A side toward the outer peripheral curved surface 20b. There are three magnetic poles: a magnetic pole on the side surface 20d on the side, a magnetic pole on the side surface 20c on the block missing portion 22A side, and a magnetic pole on the outer peripheral curved surface 20b. Therefore, the number of magnetic pole peaks formed by one magnet block 20C is larger than that in the above embodiment, and in this aspect, a magnetic force pattern having five magnetic pole peaks is realized by the two magnet blocks 20A and 20C.
(Modification 2)

  In addition, the above-described embodiment can be appropriately modified into a mode as shown in FIG. The magnet roll 14B shown in FIG. 7 employs a magnet block 20D instead of the magnet block 20C of the magnet roll 14A of FIG. The magnet block 20D has a substantially triangular cross section, and has a side surface 20d (seventh surface) on the block missing portion 22 side and a side surface 20c (eighth surface) on the block missing portion 22A side. Yes. These side surfaces 20c and 20d both intersect the first imaginary line K1. Then, it is concentrated and magnetized from the side surface 20c toward the side surface 20d, and an N pole is formed on the side surface 20d and an S pole is formed on the side surface 20c.

  That is, in this magnet roll 14B, similarly to the magnet block 20C in the magnet roll 14, the magnet block 20D has two magnetic pole peaks corresponding to the magnetic poles on the side surface 20c and the side surface 20d. That is, formation of two magnetic pole peaks is realized by one magnet block 20D. As a result, the number of magnet blocks is reduced to two while keeping the number of poles of the magnetic pattern at four (ie, without changing the number of poles), and the number of magnetic blocks is equal to or more than that of the magnetic pattern. Compared to the prior art that requires a magnet block, the number of magnet blocks 20 of the magnet roll 14B is reduced.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the number of magnet blocks included in the magnet roll is not limited to three or two, and may be increased or decreased as appropriate.

1 is a schematic perspective view of a developing roll according to an embodiment of the present invention. It is the II-II sectional view taken on the line of the image development roll shown in FIG. FIG. 3 is a sectional view of the developing roll shown in FIG. 1 taken along the line III-III. It is the figure which showed the magnetization direction of the magnet block shown in FIG. It is the figure which showed the magnetic force pattern of the magnet block shown in FIG. It is sectional drawing which showed another aspect of the magnet roll shown in FIG. It is sectional drawing which showed another aspect of the magnet roll shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Developing roll, 12 ... Sleeve, 14, 14A, 14B ... Magnet roll, 16A, 16B ... Flange, 18 ... Shaft, 20, 20A-20D ... Magnet block, 20a ... Inner curved surface, 20b ... Outer curved surface, 20c, 20d ... side face, 22, 22A ... block missing part, K1, K2 ... virtual line.

Claims (9)

A shaft, and an elongated magnet block attached along the shaft,
The magnet block includes a first surface that intersects with a first imaginary line extending along a circumferential direction of the shaft axis, and a second surface that intersects with a second imaginary line orthogonal to the axis of the shaft. And having a surface,
The magnet roll is magnetized between the first surface and the second surface, and a gap is formed on the first surface side of the magnet block. The magnet block further includes a third surface that intersects the first imaginary line and is different from the first surface;
The magnet block is magnetized between the third surface and the second surface, and an air gap is formed on the third surface side of the magnet block. Magnet roll. A shaft, and a plurality of elongated magnet blocks attached along the shaft;
The plurality of magnet blocks are continuously arranged adjacently along the circumferential direction of the axis of the shaft so that a gap is formed around the shaft.
Of the plurality of magnet blocks, an end magnet block adjacent to the gap intersects a first imaginary line extending along a circumferential direction of the shaft axis and faces the gap. And a second surface intersecting a second imaginary line orthogonal to the axis of the shaft, and is magnetized between the first surface and the second surface, Magnet roll. Among the plurality of magnet blocks, the middle magnet block where the magnet block exists on both sides,
A fourth surface that intersects the first imaginary line, a fifth surface that intersects the second imaginary line, and a surface that intersects the first imaginary line and are different from the fourth surface. 6. A sixth surface, wherein the surface is magnetized between the fourth surface and the fifth surface, and between the sixth surface and the fifth surface. 3. The magnet roll according to 3. A shaft, and an elongated magnet block attached along the shaft,
The magnet block includes a seventh surface that intersects a first imaginary line extending along a circumferential direction of the axis of the shaft, the seventh surface that intersects the first imaginary line, and the seventh surface. Has a different eighth face,
The magnet block is magnetized between the seventh surface and the eighth surface, and a gap is formed on the seventh surface side and the eighth surface side of the magnet block. A magnet roll. A magnet roll having a shaft and a long magnet block attached along the shaft;
A cylindrical sleeve for accommodating the magnet roll;
A pair of flanges attached to the end openings of the sleeve;
The magnet block has a first surface intersecting a first imaginary line orthogonal to the axis of the shaft and a second surface intersecting a second imaginary line extending in the circumferential direction of the shaft axis. And
The developing roll, wherein the magnet block is magnetized between the first surface and the second surface, and a gap is formed on the second surface side of the magnet block. A magnet roll having a shaft and a plurality of elongated magnet blocks attached along the shaft;
A cylindrical sleeve for accommodating the magnet roll;
A pair of flanges attached to the end openings of the sleeve;
The plurality of magnet blocks are continuously arranged adjacent to each other along the circumferential direction of the shaft axis so that a gap is formed around the shaft.
Of the plurality of magnet blocks, an end-side magnet block adjacent to the gap intersects a first imaginary line extending along a circumferential direction of the shaft axis and faces the gap. And a second surface intersecting a second imaginary line orthogonal to the axis of the shaft, and is magnetized between the first surface and the second surface, Development roll. Among the plurality of magnet blocks, the middle magnet block where the magnet block exists on both sides,
A fourth surface that intersects the first imaginary line, a fifth surface that intersects the second imaginary line, and a surface that intersects the first imaginary line and are different from the fourth surface. 6. A sixth surface, wherein the surface is magnetized between the fourth surface and the fifth surface, and between the sixth surface and the fifth surface. The developing roll according to 7. A magnet roll having a shaft and a long magnet block attached along the shaft;
A cylindrical sleeve for accommodating the magnet roll;
A pair of flanges attached to the end openings of the sleeve;
The magnet block includes a seventh surface that intersects a first imaginary line extending along a circumferential direction of the shaft axis, the seventh surface that intersects the first imaginary line, and the seventh surface. Has a different eighth face,
The magnet block is magnetized between the seventh surface and the eighth surface, and a gap is formed on the seventh surface side and the eighth surface side of the magnet block. The developing roll.

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